Abstract
The emission of microorganisms, especially resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA), from poultry farms is of public interest, and its occurrence and relevance are controversially discussed. So far, there are limited data on this issue. In this study, we investigated the occurrence of livestock-associated (LA)-MRSA inside and outside previously tested MRSA-positive poultry barns in Germany. In total, five turkey and two broiler fattening farms were investigated four and three times, respectively. In a longitudinal study during one fattening period, samples were collected from animals, the animals’ environment inside the barn, including the air, and the barns’ surroundings, such as ambient air and boot swabs of ground surfaces at different distances from the barn. Moreover, a cross-sectional study was carried out once inside the barns on five turkey and four broiler farms during the last third of the fatting period. In the cross-sectional study, LA-MRSA was detected in the air of most barns (7 of 9, 77.8%), as well as in many samples originating from animals, with detections levels of 50 to 54% in broiler and 62 to 77% in turkey farms. In the longitudinal study, LA-MRSA was found in the ambient air outside two turkey barns and on the ground surface on the downwind side of many (44.4%) turkey and broiler farms. The same spa types of isolates were observed inside and outside the barns. Transmission of MRSA within poultry farms, as well as emission via the airborne route, seems to be possible.
Generated Summary
This research investigated the occurrence of livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) in turkey and broiler barns, as well as the contamination of air and soil surfaces in their vicinity. The study employed both cross-sectional and longitudinal designs, sampling animals, their environment, and surrounding areas in Germany. Samples were collected from five turkey and two broiler fattening farms. The study aimed to assess the prevalence of LA-MRSA, analyze its distribution within and outside barns, and explore potential transmission routes. The cross-sectional study involved sampling inside barns during the last third of the fattening period, while the longitudinal study monitored farms over one fattening period, sampling at multiple time points. The study collected data on farms previously tested for MRSA. The study aimed to provide insights into the dissemination of MRSA in poultry farms and the potential for airborne transmission, given the public health concerns surrounding resistant bacteria from livestock.
Key Findings & Statistics
- The study included five turkey and two broiler fattening farms.
- In the cross-sectional study, LA-MRSA was detected in the air of most barns (7 of 9, 77.8%), as well as in many samples originating from animals.
- Detection levels were 50 to 54% in broiler and 62 to 77% in turkey farms.
- In the longitudinal study, LA-MRSA was found in the ambient air outside two turkey barns and on the ground surface on the downwind side of many (44.4%) turkey and broiler farms.
- The study used 85 turkey fattening farms and 40 broiler fattening farms for boot swab samples.
- The turkey farm sizes varied between 10,000 and 36,000 animals (median of 23,000).
- The sizes of broiler fattening farms varied between 35,000 and 352,000 animals (median of 250,000).
- The median number of animals in the turkey barns sampled was 5,250 (range of 4,500 to 6,000).
- In broiler barns, the median number was 34,000 (range of 8,000 to 82,000).
- Air sampling was done by impingement and filtration simultaneously.
- Collection times were 30 min for impingement and 150 min for filtration.
- Environmental samples included pooled samples of dust, feces, feed, and boot swabs.
- Sixty randomly selected animals were sampled by swabs of skin and choana.
- Air samples were taken 100 m upwind and 50 and 150 m downwind from the barn.
- In the cross-sectional study, LA-MRSA isolates were detected in the air of seven of the nine poultry farms.
- Specifically, in 4 of 5 turkey flocks and 3 of 4 broiler flocks.
- The geometric mean of the MRSA count of all positive air samples was 8.8 × 102 CFU/m³ air for impingement and 5.7 × 102 CFU/m³ for filtration.
- The respective values for Staphylococcus spp. were 1.3 × 106 CFU/m³ (impingement) and 7.6 × 105 CFU/m³ (filtration).
- In the longitudinal study, airborne MRSA isolates were found inside the barn at 13 of 26 sampling dates.
- MRSA was found in 44.4% (36/81) of all environmental boot swab samples taken from the ground surfaces on the downwind side, compared to 26.9% (7/26) on the upwind side.
- The study found 10 different spa types of MRSA.
- The majority being spa type t011 (31/80, 38.75%).
- The detection frequency of 25.9% on turkey farms is in line with the results of the national zoonosis monitoring carried out in 2010.
- The detection frequency of 25.9% on turkey farms is in line with the results of the national zoonosis monitoring carried out in 2010, which found that 19.6% of farms were positive.
Other Important Findings
- The same spa types of isolates were observed inside and outside the barns, suggesting potential transmission of MRSA within poultry farms and via the airborne route.
- In the cross-sectional study, the number of MRSA-positive animal swabs correlated positively with the number of positive air samples.
- The study identified 10 different spa types of MRSA, with the majority belonging to spa type t011.
- The prevalence of MRSA was higher in skin swab samples taken from turkeys than in those taken from broilers.
- The study confirmed that MRSA can be found in the vicinity of poultry farms, with the same spa types of isolates detected inside and outside barns.
- The study suggests that the emission of MRSA from barns is possible.
- MRSA was detected in boot swab samples on the downwind side of farms.
- The study observed a slight increase of MRSA detection in samples of animals during the fattening period.
- The study highlights that the relevance of the spread of MRSA from poultry houses to their environs is not clear.
Limitations Noted in the Document
- The study acknowledges the limitations of a cross-sectional design, which only offers a snapshot in time and may not fully capture the dynamics of MRSA presence and transmission.
- The study does not provide specific data on the management practices that may contribute to the spread of MRSA.
- The study acknowledges a lack of data on the influence of environmental factors, such as weather conditions, on the spread of MRSA.
- The study notes that the number of farms studied was limited, and therefore, some findings should be interpreted cautiously.
- The study mentions that the sampling methods used may have had different sensitivities, which could affect the results.
- The study acknowledges that the study’s preselection of MRSA-positive farms may have influenced the results.
- The study recognizes that additional factors, such as topography and rain, could have influenced the results.
Conclusion
This study provides evidence of LA-MRSA presence in turkey and broiler barns, with airborne MRSA detected both within and around the farms. The consistent detection of the same spa types inside and outside the barns suggests potential for airborne transmission. The study found that the MRSA in poultry farms, as well as emission via the airborne route, seems to be possible. The study confirms that MRSA can be found in the vicinity of poultry farms, with the same spa types of isolates detected inside and outside barns, supporting the potential for airborne transmission. Given the study’s findings, measures to mitigate the spread of MRSA, particularly those that address airborne transmission, may be beneficial. Further research is warranted to clarify the specific factors that contribute to MRSA spread and to evaluate the effectiveness of different control strategies in poultry farming.